The controversial sand vests, which weigh between 2.7 and 13lbs, are being used by 200 schools in the country despite some parents criticising them. Schools say the vests, which cost between £124 and £150, are very effective at calming down hyper children and those with attention deficit hyperactivity disorder (ADHD). They also say it’s a better way at tackling the problem than using drugs such as Ritalin.